Influence of Ta on the intermediate temperature creep behavior of a single crystal superalloy

The influence of Ta on the intermediate temperature creep behavior and deformation mechanism in a Ni-based single crystal superalloy has been investigated at 760 degrees C and 750 MPa. The results indicate that there is a sig-nificant increasing of creep rupture life after the addition of Ta. Lattice misfit between gamma and gamma ' phase at 760 degrees C increases in the Ta-containing alloy. Microstructure showed that the formation of stacking faults in the gamma matrix and denser dislocation network at the gamma/gamma ' interfaces caused by Ta addition are found during the primary creep stage. And a large amount of stacking fault locks which act as an important pattern in the strengthening generate in the gamma ' precipitates, resulting in a lower steady state creep rate and longer steady state creep life in Ta-containing alloy. And possible formation mechanism of the stacking fault locks is also discussed.